Twelve days after Lincoln's assassination, John Wilkes Booth was shot and killed by soldiers at a farm in Virginia, and his body taken to New York for autopsy and identification. Booth was a famous actor, and his body was easily recognized. But soon after his death conspiracy theories began circulating, claiming that Booth didn’t die, but had escaped and lived for years.
At Wonders and Marvels, Jack El-Hai writes about the FBI file on John Wilkes Booth. The first official Bureau of Investigation opened in 1908, and the first documents on Booth came in the 1920s. A Missouri man wrote to the bureau claiming that Booth was his next door neighbor. Nothing came of those allegations, but the FBI investigated Booth’s life twice more, in 1948 and 1977 at the behest of the National Park Service. In the 1948 case, they examined the boot that Booth wore during his initial escape. (The boot was cut off by Dr. Samuel Mudd as he was treating Booth’s broken leg.) There was writing on the inside of the boot, but the FBI couldn’t decipher it. In 1977, the FBI examined Booth’s diary for secret or invisible writing.
The bureau didn’t find anything beyond his melodramatic and arrogant prose, written in distinctly visible lettering:
“Our country owed all her troubles to him[Lincoln], and God simply made me the instrument of his punishment…I have too great a soul to die like a criminal . . . spare me that and let me die bravely.”